Transmission system



y 1930- c. w. HOUGH 1,757,121

TRANSMISSION SYSTEM Filed May 12, 1928 I" INVEN'TOR. H (72521 12 7% ATTORNEY Patented May 6, 1930 UNITED STATES PATENT oFFmE CLINTON W. HOUGH, F BOONVILLE, NEW YORK, ASSIGNOR, BY MESNE ASSIGNMENTS, TO FEDERAL TELEGRAPH COMPANY, A CORPORATION OF CALIFORNIA TRANSMISSION SYSTEM Application filed May 12, 1928. Serial No. 277303.

My invention relates broadly to transmission systems and more particularly to the light-current variations.

.transmission of such frame.

Another object of my invention is to provide an improved transmission circuit for picture transmission wherein a plurality .of branch circuits are provided for continuous transmission during the time interval that ordinarily no transmission occurs.

A still further object of my invention is to provide a more efiicient system for transmission of motion pictures whereby continuous transmission of light impulses is obtained and no lapse of transmission occurs during the time elapsed when one picture frame is being moved out of position and another picture frame being moved into position for transmission.

A more comprehensive understanding may be had of the system I employ from the specification to follow and by reference to the accompanying drawings.

In my work on television and particularly in connection with the transmission and reception of motion pictures by means of television systems utilizing space radio, wired radio or over wire lines without the use of carrier systems I have found it necessary to utilize the system of picture film movement and projection employed in the motion picture industry, that is, an intermittent movement of the picture film so that successive picture frames of the motion picture film to be transmitted are moved into the transmitting position and held stationary in such position during the period required for the During the period of time required for the movement of the picture frame previously transmitted from the transmitting position and the m0vement of the succeeding frame into transmitting position there can be no direct transmission as the film is in motion. The sequence of operation is then, (a) "transmission of first picture frame, (6) cessation of transmission during displacement movement of the frame just transmitted and movement into transmitting position of second picture frame, (a) transmission of second picture frame, and so on. This results in the transmission of successive groups of impulses each group rep resenting one frame with a time interval between each group.

My present invention consists of methods for repeating each successive group of impulses during the period taken for the movement of successive frames of the picture film into transmitting position thereby securmg continuous transmission of picture impulses rather than the intermittent transmission previously employed.

This is accomplished by passing the electrical impulses representing a picture frame through two or more parallel circuits which have the electrical characteristics required to advance or retard the time relation of the electrical impulses passing through them. The outputs of such parallel circuits are combined so that the groups of impulses impressed simultaneously upon their input terminals are delivered at the combined output terminals at successive time intervals. In this way an original group of impulses will be repeated one or more times in the output circuit before the second group of original impulses is transmitted. This has the effect of causing the transmission of the first picture frame a multiple number of times; transmission goes on during the time that the picture frame is being changed from one to another, resulting in. substantially continuous instead of intermittent transmission with consequent greater illumination and clarity of the received pictures.

My invention will be more fully understood from the specification hereinafter following by reference to the accompanying drawings wherein:

Figure 1 is a diagrammatic view showing the relation of parts in the television system of my invention and Fig. 2 shows a wiring diagram for carrying out the principles of my invention.

In the accompanying drawing Fig. 2 shows one method of accomplishing the above result. Variable light impulses from a motion picture film scanner 12 actuate a light sensitive element 1 actuating an amplifier 2. Output 15 of this amplifier is conducted to three parallel circuits 16, 17 and 18 in two of which are connected the retardation networks 5 and 6. Terminals of these three parallel circuits are connected to amplifiers 3, 7 and 8. The amplifying characteristics of these amplifiers 3, 7 and 8 are such as to equahze the outputs of the three parallel circuits at the amplifier terminals and the latter are connected in parallel as the'output terminals 4 of the time base repeater WhlCh this circuit may be ca led. 7

Assuming the transmission of sixteen motion icture frames per second (the standard speed of motion picture projection) and that each frame is in its stationary pro ect1on or transmission position for a time interval of 1/48th second and the time interval required to move the successive film frame into its stationar transmitting position is 1/24th second,tl 1 en the group 0 picture nnpulses may be repeated twice during this 1/24th second thus providing three separate groups of identical im ulsesduringsuccessivetimeintervals before t e beginning of transmission of the succeeding frame, thereb providing means for securing three times t e energy for operation of transmitting and receiving equipment. In this example the three parallel circuits would have retardation time values of 0,1/48, and 1/24th second.

The retardation systems 5 and 6 include inductive reactance and are designed by the equation:

' E 1 l R L in which i=the current in amperes at time t after closing the switch.

R=total resistance of circuit in ohms.

E=E. M. F. of supply.

L=the co-eflicient of self-induction of the circuit, in henries;

t=the number of seconds clasping after the switch is closed;

e=the base of natural logarithms=2.718.

Fig. 2 is a diagram of a circuit arrangement embodying my invention, in which an incandescent bulb 11, a rotating disk 12, a motion picture film 10 and lens 13 produce variations of light intensity and such variations of light intensity produce variations in the resistance of the hght sensitive cell 1. The systems for producin variations of current from variations of ight intensity are many, and the embodiment of my invention is not to be limited to the system illustrated.

Variations in the resistance of light-sensitive cell I produce corresponding variations of current in the circuit 14. The variations of current in circuit 14 produce variations in the input and output circuitsof amplifier 2. The current variations in the output circuit of amplifier 2 is distributed to the circuits 5, 6 and 9.

Circuit 9 is a coupling circuit between the amplifier 2 and the equalizing amplifier 3. The output of the amplifier 3 is connected to the output leads 4. The coupling'circui't 9 is balanced so that the current retardation value is negligible. The circuit 5 is a retardation circuit having a retardation value c uivalent to a line 3880 miles in length. T is value was determined in view of the usual time of exposure allowed each picture and the time interval of l/l6second. The circuit 5 also couples through an equalizing amplifier 8, to output circuit 4. Circuit 6 is a retardation circuit having a retardation value equivalent to a line 7760 miles in length. Circuit 6 is coupled to an equalizing amplifier 7, the output of which is connected to the output circuit 4.

In the retardation circuits 5 and 6 the current from the output of the amplifier 2 cannot at once rise toits highest value; it takes an appreciable time and this will depend upon the ratio of the inductance to the resistance of the circuit. The constants of the circuit can be determined by the afore-mentioned equation which is commonly referred to as the logarithmic rise of current.

While I have described a preferred embodiment of my invention I desire that it be understood that modifications may be made by those skilled in the art and that no limitations are intended beyond those imposed by the scope of the appended claims.

What I claim and desire to secure by Letters Patent of the United States is as follows:

1. In a system for transmission of motion pictures, the combination of light-sensitive apparatus producing variations of current, means for amplifying said current variations, and means for delaying the current through a plurality of circults from said amplifier to a plurality of equalizing ampli- 2. In a system for transmission of motion pictures, the combination of light-sensitive apparatus whereby variations of light intensity cause variations of current, an amplifier associated with said light sensitive apparatus to amplify said current variations, a plurality of circuits associated with the output of said amplifier and having different retardation values for the current through said circuits.

3. In an apparatus for the transmission of motion pictures the combination of lightsensitive" apparatus whereby variations in light intensity produce variations of current in the input circuit of an amplifier associated with said light-sensitive apparatus, a plurality of circuits interconnecting said amplifier with a second amplifier, said circuits designed to have different values for retarda- 7 tion of the current therein.

4. In an apparatus for the transmission of successive groups of light variations, lightsensitive apparatus for converting light impulses into current impulses, means for amplifying said current impulses, retardation circuits inter-connecting said amplifying means with a second amplifying means, whereby the current in the output circuit of said second amplifying means has a phase displacement as determined by said retardation circuits.

5. In an apparatus for the transmission of a successive group of pictures, light-sensitive apparatus for converting variations of light into current variations, the combination of an amplifying means to amplify said current variations, circuits inter-connecting said amplifying means with a second amplifying means, said circuits having the property 0 retarding said current variations and delivering said current variations to said second amplifying means at different, predetermined time intervals.

6. In an apparatus for the transmission of motion pictures, means for converting variations of light into variations of current, means associated with said converting means for producing a time displacement of said current variations whereby said current variations are admitted to an output circuit during the time intervals between exposure of successive pictures.

7. In an apparatus for the transmission of a series of pictures, means for converting light variations into current variations, circuits associated with said light conversion means said circuits having current retardation values, a second circuit associated with said conversion means and having a zero retardation value, said retardation circuits designed to deliver said current variations to an output circuit when the circuit having no retardation value is delivering no current to said output circuit.

8. In an apparatus for the transmission of motion pictures, means for causing light variations to produce current variations, a plurality of circuits associated with said means whereby the current variations are retarded and delivered to an output circuit during the time interval when no current variations are produced.

9. In an apparatus for the transmission of motion pictures, light-sensitive means for producing current variations in an output circuit, an output circuit comprisin a plurality of retardation circuits where y current variations occur in said circuit when no light variations actuate said 1ight-sensitive means.

10. In an apparatus for the transmission of motion pictures, light-sensitive means for producing variations of current in the input circuit of an amplifying means when light variations actuate said light-sensitive means,

a plurality of circuits associated with said amplifying means and associated with a second amplifying means, said circuits havin a retardation effect on the current delivers to said second amplifying means whereby GLIN TON W. HOUGH. 

